vin BOTANY 



(6) The root . . . . . . .131 



(c) Secondary growth in thickness of the cornius . . 140 

 2. Adaptations of the Cormus to its Mode of Life and to the Environment 165 



A. Autotrophic cormophytes . . . . . .165 



(a) Adaptations to the humidity of the environment . .165 



(b) Adaptations for obtaining light . . . .181 



(c) Adaptations of green cormophytes to special modes of 



nutrition . . . . . . .185 



B. Heterotrophic cormophytes . % . .188 

 II. Organs of Reproduction ... .192 



SECTION IV. THE THEORY OF DESCENT AND THE ORIGIN 

 OF NEW SPECIES 



A. The theory of descent .... .206 



B. Formation of species and the origin of adaptations .... 210 



DIVISION II. PHYSIOLOGY 



Essential phenomena of life . . . . . . .215 



SECTION I. METABOLISM 



I. The Chemical Composition of the Plant ... . 220 

 II. The Nutrient Substances ; their Absorption and their Movement within 



the Plant ....... .222 



III. The Assimilation of the Food Materials . . .247 



IV. Translocation and Transformation of Assimilates . . . 263 



V. Respiration and Fermentation ... . 269 



SECTION II. DEVELOPMENT 



I. Introductory Remarks ... . . 278 



1. The measurement of growth ... . 278 



2. The phases of growth .... .282 



II. The Factors of Development ... . 288 



A. External factors ... .288 



B. Internal factors .... .296 

 IH. The Course of Development and its Dependence on External and 



Internal Factors . . 301 



A. Resting condition and the commencement of growth . . 303 



B. Growth and cell division ...... 306 



C. Further periodic changes in vegetative form . . 307 



D. Duration of life .... . 309 



E. Reproduction ..... . 310 



F. Heredity, variability, origin of species . . . 316 



